Packaged direct fired heater



Jan. 4, 1966 J. J. GRIFFIN PACKAGED DIRECT FIRED HEATER 3 Sheets-Sheet 3 Filed July 22, 1964 I I I w/////// 1,/// 1 1 1 I 1 11 1/ 1/ INVENTOR H/V f6lFFlN BY /..4, {A4

ATTORNEY United States Patent M 3,227,143 PACKAGED DIRECT FIRED HEATER John J. Griffin, Huntington, N.Y., assignor to Alcorn Combustion Company, New York, N .Y., a corporation of Delaware Filed July 22, 1964, Sel. No. 384,442 2 Claims. (Cl. 122-356) widths of shipping modules.

In translating dimensional limitations into the design of process heaters, it should be kept in mind that dire-ct flame impingement onto tubes must usually be avoided. Accordingly, one objective of this design is to fit suificient high temperature tube surface into the space dictated on one hand by available width and height and on the other hand by flame impingement.

Coils mounted in radiant section of process heaters generally accommodate higher temperature services than do coils mounted in convection sections of the same heaters. High temperature heat transfer services are usually ascribed a premium from an overall plant design point of view. This premium becomes clearly understandable when one reflects on the many low temperature heat recovery opportunities which go unclaimed in many plants. However, even though high temperature services are in demand, a manufacturer of process heaters usually regards it desirable that each heater be able to justify its own thermal efficiency. So it is a further objective of this design to put a predominant portion oftheusable heat into high temperature service while also recovering as much heat as is economically feasible at lower temperatures.

The heater here presented achieves the foregoing objectives in an interesting and novel manner. More particularly, this heater includes a box-shaped module which defines a refractory lined furnace chamber. An interior baffle projects downward'from the roof to divide the furnace chamber into a radiant section and a convection section. The bafiie is spaced from the floor so that the convection section includes only a portion of the height of the chamber and so that combustion gases are permitted to pass under the baffle from the radiant section to the convection section. The space below the convection section forms part of the radiant section. Field mountable burners penetrate openings in side walls of the module to deliver fuel and air for combustion in the radiant section. Long straight high temperature service tubes are arranged along the length of the furnace chamber. These long straight tubes comprise upper tubes and lower tubes. The upper tubes are mounted against the roof and against the side wallsabove the burners. The lower tubes are mounted against the floor and the side Walls below the burners. The lower tubes are exposed to radiant heat transfer from the combustion gases over substantially their entire lengths. The upper tubes are exposed to radiant heat transfer as they traverse the radiant section, but after penetrating the battle into the convection section, these upper tubes are exposed only to convective heat transfer. The upper tubes are provided with extended surfaces in the convection section. By employing extended surface heat input to the portions of these upper tubes in the convection section is made substantially equal to the heat input to the portions of 3,227,143 Patented Jan. 4, 1966 these same tubes which are exposed to radiant transfer. Thus each of the upper tubes forms a portion of a high temperature service coil with a heat input approximately equal to a fully radiant lower tube of the same diameter. Of course, conventional low temperature services can also be provided in the convection section.

Basically, this teaching offers improved compactness. The long straight tube lengths promote economy. Using convective heat transfer in a high temperature service improves the attractiveness of the heater from an overall plant design point of view and makes higher thermal efliciency of the heater possible. Further, tubes in the convection section are arranged to see only lower tubes rather than burners so their lives are prolonged.

These and other features will appear more fully from the accompanying drawings wherein:

FIGURE I is a longitudinal vertical section of a preferred embodiment of this invention.

FIGURE II is a transverse vertical section taken through the convection section.

FIGURE III is a longitudinal section taken along line IIIII-I of FIGURE 1.

In the drawings elongated box-like setting 1 is designed for convenient shipment. This setting includes flat floor 2 opposed upright side walls 3 and 4 as well as upstream 6 and downstream 7 end walls and flat roof 8. The overall distance between the outer extremities of side walls 3 and 4 as well as the overall distance between the upper extremity of the roof 3 and the lower extremity of the floor 2 are arranged to accommodate transportation clearance for this module. Length is usually far less critical.

Both a radiant furnace section and a convection section are fashioned .in the same shipping module. Battle 9 depends vertically downward fro-m roof 2 to substantially divide the furnace chamber into radiant furnace section 11 and convection section 12. Radiant section 11 is defined by floor 2, roof 8, side walls 3 and 4, the upstream side of baffle 9 and upstream end wall 6. Lower end 13 of battle 9 is spaced from floor 2 to provide passage 14 which permits the exit of hot combustion gases from radiant section 121. From passage 14 the gases enter upwardly into convection section 12 which is enclosed on five sides by the downstream side of baflie 9, side walls 3 and 4, roof 8 and downstream end Wall 7. Roof 8 defines stack port 16 which allows exhausting of the gases from convection section 12. A stack 17 is shipped as a separate item from the basic heater module and stack 17 is connectable to roof 8 about stack port 16.

Sufiicient space must be allowed for burners to develop their required flame patterns while as little burden as possible is imposed upon critical shipping dimensions. Toward this objective burners 18 are arranged to penetrate setting 1 via side walls 3 and 4; further, these burners are staggered on opposite sides along the length of radiant section 11 so that each burner has a full width of the chamber for development of its flame burst. To allow greater flexibility in the selection of fuels, a target area 19 is provided on the side wall opposite each burner 18. Hot gases flow downward from each target area 19 so trapping of heat is avoidedf Burners 18 may be field mounted in a manner well known to the fired heater indus- For thermal efficiency and for promoting high temperature service upper tubes 21 are continued from radiant section 11 through convection section 12. Extended surface 22 is added to the portions of upper tubes 21 in convection section 12 to make up for lower temperatures therein. The arrangement of inlets 23, wall tubes 24, lower tubes 26, and outlets 27 are otherwise well known. Low temperature service .is available from convection coil 28, which may provide preheating as here shown.

It will be apparent to those skilled in fired heater design means in the roof defining a stack port in flow series that wide deviations may be made in the detail of this connection with the convection section, preferred embodiment without departing from the main a stack connectable to the roof about the stack port theme of invention defined by the following claims. to vent the combustion gases from the convection What is claimed is:

1. A fired heater comprising in combination an elongated box-like setting arranged for shipment as a single module and having a flat floor and two opposed upright side walls as well as upright upstream and downstream end walls and a flat roof,

section to the atmosphere,

a low temperature coil mounted in the convection section,

means for circulating a process fluid through the low temperature coil,

a high temperature coil comprising a plurality of tubes the floor and the roof and the side walls and the end mounted longitudinally relative the setting and ex- Walls all cooperating to define a chamber there within, tending substantially the length of the setting between the overall distance between the outer extremities of the the upstream and the downstream end walls,

side walls as well as the overall distance between at least one of the tubes penetrating the battle and the upper extremity of the roof and the lower extraversing longitudinally through the convection sectremity of the floor arranged to accommodate transtion,

portation clearances of the module, extended surface depending from the last mentioned a bafiie depending vertically downward from the roOf tube in the convection section so that heat flux into transversely relative the setting and projecting downthe last mentioned tube from convective transfer is ward into the chamber to substantially divide the approximately the same as the heat flux to the porchamber into a radiant section and a convection section Oflhilt 117E exposed to l'fldjflnl transfer,

tion, means for circulating a process fluid through the high the upstream end wall and the baffle and the roof and mmimmwre the floor and the side walls defining the radiant sec- The heater damn 1 Wm] on, a plural ty of burners arranged on the opposed side the downstream end Wall and the bathe and the roof Walls m alternating Telafionshlp therealong c d the Sidg Walls definim the com/action Section in at least two burners on at least one of the side walls In a spaced from each other so that the wall portion Spaced rclauortshlp mlwve the floor therebetween forms a target area for a burner penea burner operatively connectable to the settmg and Uatingthe opposite side WalL penetrating the setting via one of the side walls to project horizontally therein for introducing fuel and References Cit d by th E a i afilr toddefitne horizontal transverse flame burst in UNITED STATES PATENTS era ran secron 7 i 2,220,387 11/1940 Baker 122-356 X the side wall opposite the burner defining a target zone 30 2,237,502 4/1941 Rickerman 1Z2 356 X against which the flame burst can project,

the baffle having a lower end spaced from the floor to define a passage therebetween to communicate the radiant section with the convection section for admitting combustion gases thereto,

JAMES W. W ESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, 111., Examiner.

4O KENNETH W. SPRAGUE, Assistant Examiner. 

1. A FIRED HEATER COMPRISING IN COMBINATION AN ELONGATED BOX-LIKE SETTING ARRANGED FOR SHIPMENT AS A SINGLE MODULE AND HAVING A FLAT FLOOR AND TWO OPPOSED UPRIGHT SIDE WALLS AS WELL AS UPRIGHT UPSTREAM AND DOWNSTREAM END WALLS AND A FLAT ROOF, THE FLOOR AND THE ROOF AND THE SIDE WALLS AND THE END WALLS OF COOPERATING TO DEFINE A CHAMBER THERE WITHIN, THE OVERALL DISTANCE BETWEEN THE OUTER EXTREMITIES OF THE SIDE WALLS AS WELL AS THE OVERALL DISTANCE BETWEEN THE UPPER EXTREMITY OF THE ROOF AND THE LOWER EXTREMITY OF THE FLOOR ARRANGED TO ACCOMMODATE TRANSPORTATION CLEARANCES OF THE MODULE, A BAFFLE DEPENDING VERTICALLY DOWNWARD FROM THE ROOF TRANSVERSELY RELATIVE THE SETTING AND PROJECTING DOWNWARD INTO THE CHAMBER TO SUBSTANTIALLY DIVIDE THE CHAMBER INTO A RADIANT SECTION AND A CONVECTION SECTION, THE UPSTREAM END WALL AND THE BAFFLE AND THE ROOF AND THE FLOOR AND THE SIDE WALLS DEFINING THE RADIANT SECTION, THE DOWNSTREAM END WALL AND THE BAFFLE AND THE ROOF AND THE SIDE WALLS DEFINING THE CONVECTION SECTION IN SPACED RELATIONSHIP RELATIVE THE FLOOR, A BURNER OPERATIVELY CONNECTABLE TO THE SETTING AND PENETRATING THE SETTING VIA ONE OF THE SIDE WALLS TO PROJECT HORIZONTALY THEREIN FOR INTRODUCING FUEL AND AIR TO DEFINE A HORIZONTAL TRANSVERSE FLAME BURST IN THE RADIANT SECTION, THE SIDE WALL OPPOSITE THE BURNER DEFINING A TARGET ZONE AGAINST WHICH THE FLAME BURST CAN PROJECT, THE BAFFLE HAVING A LOWER END SPACED FROM THE FLOOR TO DEFINE A PASSAGE THEREBETWEEN TO COMMUNICATE THE RADIANT SECTION WITH THE CONVECTION SECTION FOR ADMITTING COMBUSTION GASES THERETO, 